“Google is present at almost all levels of the so-called adtech supply chain,” Margrethe Vestager, the executive vice president of the European Commission, said in a statement. “Our preliminary concern is that Google may have used its market position to favor its own intermediation services.”

“Not only did this possibly harm Google’s competitors but also publishers’ interests, while also increasing advertisers’ costs,” added Ms. Vestager, who oversees digital and competition policy.

The new charges against Google are part of a long-running effort by the European authorities to clamp down on the world’s largest technology companies. Apple and Meta, which owns Facebook and Instagram, are also the subjects of antitrust investigations. Last year, the European Union passed new antitrust and digital services laws to tighten oversight of the biggest tech companies. And on Wednesday, the European Parliament, a legislative branch of the European Union, passed a draft law regulating artificial intelligence.

In recent years, the European authorities have fined Google billions of dollars over what they say are antitrust violations related to its Android mobile operating system, shopping service and another piece of its advertising business. All the cases remain tied up in court after legal appeals by Google.

With the new charges, the European Commission unveiled what is known as a “statement of objections” against Google, outlining why it believes the company has violated antitrust laws. It is one step in what could be a long process before final decisions are made about whether to impose a fine of up to 10 percent of Google’s global revenue or to order other changes to its business practices. A settlement could also be reached.